Fas Associated Factor 1 (FAF1)

Northern blot analysis revealed a single FAF1 mRNA transcript of 2.8 kb to be most abundant in testis, slightly less abundant in skeletal muscle and heart, followed by prostate, thymus, ovary, small intestine, and colon. Expression was detected in all other tissues tested with the exception of peripheral blood leukocytes. By immunoblotting with a mouse polyclonal antibody to FAF1, a 74-kD protein was detected in 6 of 8 tumor cell lines. A 40-kD protein was detected in 1 of the 2 remaining cell lines. Interaction of FAF1 and FAS was shown in both the yeast 2-hybrid and the GST pull-down assay systems. The N-terminal 201 amino acids of FAF1, containing a ubiquitin homology domain, bound to the FAS death domain but not to a death domain mutant in the yeast 2-hybrid system.